import turtle

def draw():
    # 第1段
    turtle.forward(20)
    turtle.left(90)

    turtle.forward(20)
    turtle.right(90)

    # 第2段
    turtle.forward(20)
    turtle.left(90)

    turtle.forward(20)
    turtle.right(90)

    # 第3段
    turtle.forward(20)
    turtle.left(90)

    turtle.forward(20)
    turtle.right(90)

    # 第4段
    turtle.forward(20)
    turtle.left(90)

    turtle.forward(20)
    turtle.right(90)


if( __name__ == "__main__" ):
    draw()
    turtle.mainloop()
